EP4739719A1

EP4739719A1 - Gradient polymer

Info

Publication number: EP4739719A1
Application number: EP23944060.5A
Authority: EP
Inventors: Fanwen Zeng; Shiling Zhang; Inna Shulman; Xiadong Lu; Ying O'connor
Original assignee: Dow Global Technologies LLC; Rohm and Haas Co
Current assignee: Dow Global Technologies LLC; Rohm and Haas Co
Priority date: 2023-07-06
Filing date: 2023-07-06
Publication date: 2026-05-13
Also published as: KR20260032591A; CN121241075A; WO2025007330A1

Abstract

Gradient polymer is provided comprising: 5-35 wt% structural units of (meth)acrylic acid monomer; 35-65 wt% structural units of C_1-8 alkyl (meth) acrylate monomer; >10-30 wt% structural units of specialized associative monomer having structure (I) wherein R¹ is selected from a linear saturated C_12-26 alkyl group; R² is selected from a hydrogen and a methyl group and n is 10-30; 0.01-2 wt% structural units of multiethylenically unsaturated monomer; wherein the gradient polymer comprises <0.05 wt% structural units of sulfonated monomer; wherein the gradient polymer comprises <0.02 wt% structural units of monomer having structure (II) wherein R³ is selected from -H and -CH₃; wherein R⁴ is selected from -H and a -C_1-4 alkyl group; wherein R⁵ is selected from -C_1-4 alkyl group; wherein α is 0-50; wherein b is 0-20; wherein c is 0-50; wherein α+c is 1 to 100 and wherein d is 1-4; and wherein the gradient polymer has a gradient polymeric morphology.

Description

GRADIENT POLYMER

The present invention relates to a gradient polymer. In particular, the present invention relates to a gradient polymer comprising: (a) 5 to 35 wt%, based on dry weight of the gradient polymer, of structural monomer units of (meth) acrylic acid monomer; (b) 35 to 65 wt%, based on dry weight of the gradient polymer, of structural monomer units of C_1-8 alkyl (meth) acrylate monomer; (c) ＞ 10 to 30 wt%, based on dry weight of the gradient polymer, of structural monomer units of a specialized associative monomer having structure I
wherein each R¹ is independently selected from a linear saturated C_12-26 alkyl group; wherein each R² is independently selected from a hydrogen and a methyl group and wherein n is 10 to 30; (d) 0.01 to 2 wt%%, based on dry weight of the gradient polymer, of structural monomer units of multiethylenically unsaturated monomer; wherein the gradient polymer comprises ＜ 0.05 wt%, based on dry weight of the gradient polymer, of structural monomer units of sulfonated monomer; wherein the gradient polymer comprises ＜ 0.02 wt%, based on dry weight of the gradient polymer, of structural monomer units of monomer having structure II
wherein each R³ is independently selected from -H and -CH₃; wherein each R⁴ is independently selected from -H and a -C_1-4 alkyl group; wherein each R⁵ is independently selected from a -C_1-4 alkyl group; wherein a is 0 to 50; wherein b is 0 to 20; wherein c is 0 to 50;wherein a + c is 1 to 100; and wherein d is 1 to 4; and wherein the gradient polymer has a gradient polymeric morphology.
Amino acid based surfactants have an array of desirable properties for use in personal care products (e.g., shampoos) . Such surfactants are often naturally derived and readily biodegradable. They are very mild and cause less irritation to skin and hair compared to more traditional sulfate and sulfonate based surfactants like sodium lauryl sulfate and sodium lauryl ether sulfate. They tend to demonstrate lower toxicity and reduced negative impact on the environment than more traditional sulfate and sulfonate based surfactants. The have good cleaning and foaming properties.
Notwithstanding, formulations comprising amino acid based surfactants are challenging to efficiently thicken. Some conventional thickeners achieve target viscosity at high usage levels which may negatively impact foaming performance. In other cases, conventional thickeners can provide adequate thickening, but the formulation viscosity is sensitive to changes in temperature; becoming watery at a high temperature and jelly like at low temperatures. Some conventional thickeners such as xanthan gum or cellulose esters exhibit potential compatibility issues resulting in phase separation.
Accordingly, there remains a continuing need for viscosity modifiers that facilitate formulation of aqueous cleaning products, in particular amino acid surfactant containing aqueous cleaning products (e.g., shampoo) , with increased viscosity at low shear rates while maintaining desired flow properties at higher shear rates.
The present invention provides a gradient polymer comprising: (a) 5 to 35 wt%, based on dry weight of the gradient polymer, of structural monomer units of (meth) acrylic acid monomer; (b) 35 to 65 wt%, based on dry weight of the gradient polymer, of structural monomer units of C_1-8 alkyl (meth) acrylate monomer; (c) ＞ 10 to 30 wt%, based on dry weight of the gradient polymer, of structural monomer units of a specialized associative monomer having structure I
wherein each R¹ is independently selected from a linear saturated C_12-26 alkyl group; wherein each R² is independently selected from a hydrogen and a methyl group and wherein n is 10 to 30; (d) 0.01 to 2 wt%%, based on dry weight of the gradient polymer, of structural monomer units of multiethylenically unsaturated monomer; wherein the gradient polymer comprises ＜ 0.05 wt%, based on dry weight of the gradient polymer, of structural monomer units of sulfonated monomer; wherein the gradient polymer comprises ＜ 0.02 wt%, based on dry weight of the gradient polymer, of structural monomer units of monomer having structure II
wherein each R³ is independently selected from -H and -CH₃; wherein each R⁴ is independently selected from -H and a -C_1-4 alkyl group; wherein each R⁵ is independently selected from a -C_1-4 alkyl group; wherein a is 0 to 50; wherein b is 0 to 20; wherein c is 0 to 50;wherein a + c is 1 to 100; and wherein d is 1 to 4; and wherein the gradient polymer has a gradient polymeric morphology.
The present invention provides a gradient polymer comprising: (a) 5 to 35 wt%, based on dry weight of the gradient polymer, of structural monomer units of (meth) acrylic acid monomer; (b) 35 to 65 wt%, based on dry weight of the gradient polymer, of structural monomer units of C_1-8 alkyl (meth) acrylate monomer; (c) ＞ 10 to 30 wt%, based on dry weight of the gradient polymer, of structural monomer units of a specialized associative monomer having structure I; wherein the structural monomer units of specialized associative monomer having structure I is a blend of a first specialized associative monomer having structure Ia
wherein each R^1a is independently selected from a linear saturated C_12-19 alkyl group; wherein each R^2a is independently selected from a hydrogen and a methyl group and wherein na is 10 to 30; and a second specialized associative monomer having structure Ib
wherein each R^1b is independently selected from a linear saturated C_20-26 alkyl group; wherein each R^2b is independently selected from a linear saturated hydrogen and a methyl group; and wherein nb is 10 to 30; wherein the gradient polymer comprises ＜ 0.05 wt%, based on dry weight of the gradient polymer, of structural monomer units of sulfonated monomer; wherein the gradient polymer comprises ＜ 0.02 wt%, based on dry weight of the gradient polymer, of structural monomer units of monomer having structure II; wherein each R³ is independently selected from -H and -CH₃; wherein each R⁴ is independently selected from -H and a -C_1-4 alkyl group; wherein each R⁵ is independently selected from a -C_1-4 alkyl group; wherein a is 0 to 50; wherein b is 0 to 20; wherein c is 0 to 50; wherein a + c is 1 to 100 and wherein d is 1 to 4; and wherein the gradient polymer has a gradient polymeric morphology.

DETAILED DESCRIPTION

We have surprisingly found that gradient polymer, as described herein, facilitates the formulation of aqueous cleaning products, in particular amino acid surfactant containing aqueous cleaning products (e.g., shampoo) , to increase viscosity at low shear rates while maintaining flow properties of the product at higher shear rates.
Unless otherwise indicated, ratios, percentages, parts, and the like are by weight.
Percentages of monomer units in a polymer are percentages of solids or neat monomer weight, i.e., excluding any water present in a polymer emulsion.
The term "structural monomer units" as used herein and in the appended claims refers to the remnant of the indicated monomer; thus a structural monomer unit of ethyl acrylate is illustrated:
where the dotted lines represent the points of attachment to the polymer backbone.
The term “ (meth) acrylic acid” as used herein and in the appended claims is intended to serve as a generic expression embracing both acrylic acid and methacrylic acid.
The term “ (meth) acrylate” as used herein and in the appended claims is intended to serve as a generic expression embracing both acrylate and methacrylate.
The term "gradient polymeric morphology" as used herein and in the appended claims refers to a polymer having a continually changing monomeric compositional content. The preparation of gradient polymers having a gradient polymeric morphology is well known in the art. U.S. Patent No. 3,804,881, hereby incorporated by reference in its entirety, discloses a process for preparing gradient polymers having a gradient polymeric morphology wherein the process comprises polymerizing at least one primary polymerizable monomer feed varying in compositional content by continuously adding at least one different secondary polymerizable monomer feed to the at least one primary polymerizable monomer feed.
Preferably, the gradient polymer of the present invention comprises: (a) 5 to 35 wt%(preferably, 10 to 35 wt%; more preferably, 20 to 34 wt%; most preferably, 26 to 32 wt%) , based on dry weight of the gradient polymer, of structural monomer units of (meth) acrylic acid monomer; (b) 35 to 65 wt% (preferably, 40 to 60 wt%; more preferably, 45 to 55 wt%; most preferably, 48 to 54 wt%) , based on dry weight of the gradient polymer, of structural monomer units of C_1-8 alkyl (meth) acrylate monomer; (c) ＞ 10 to 30 wt% (preferably, 12 to 30 wt%; more preferably, 15 to 25 wt%; most preferably, 16 to 20 wt%) , based on dry weight of the gradient polymer, of structural monomer units of a specialized associative monomer having structure I
wherein each R¹ is independently selected from a linear saturated C_12-26 alkyl group (preferably, C_12-24 alkyl group; more preferably, C_14-24 alkyl group; most preferably, C_16-22 alkyl group) ; wherein each R² is independently selected from a hydrogen and a methyl group (preferably, wherein R² is a methyl group) and wherein n is 10 to 30 (preferably, 12 to 30; more preferably, 15 to 28; most preferably, 18 to 26) ; and (d) 0.01 to 2 wt% (preferably, 0.05 to 1 wt%; more preferably, 0.08 to 0.5 wt%; most preferably, 0.1 to 0.2 wt%) , based on dry weight of the gradient polymer, of structural monomer units of multiethylenically unsaturated monomer; wherein the gradient polymer comprises ＜ 0.05 wt% (preferably, ＜ 0.01 wt%; more preferagbly, ＜ 0.001 wt%; still more preferably, ＜ 0.0001 wt%; most preferably, less than detectable limit) , based on dry weight of the gradient polymer, of structural monomer units of sulfonated monomer (e.g., AMPS) ; wherein the gradient polymer comprises ＜ 0.02 wt%, based on dry weight of the gradient polymer, (preferably, ＜ 0.01 wt%; more preferably, ＜ 0.001 wt%; still more preferably, ＜ 0.0001 wt%; most preferably, less than detectable limit) of structural monomer units of monomer having structure II
wherein each R³ is independently selected from -H and -CH₃; wherein each R⁴ is independently selected from -H and a -C_1-4 alkyl group; wherein each R⁵ is independently selected from a -C_1-4 alkyl group; wherein a is 0 to 50; wherein b is 0 to 20; wherein c is 0 to 50;wherein a + c is 1 to 100 and wherein d is 1 to 4; andwherein the gradient polymer has a gradient polymeric morphology. More preferably, the gradient polymer of the present invention comprises: (a) 5 to 35 wt% (preferably, 10 to 35 wt%; more preferably, 20 to 34 wt%; most preferably, 26 to 32 wt%) , based on dry weight of the gradient polymer, of structural monomer units of (meth) acrylic acid monomer; (b) 35 to 65 wt% (preferably, 40 to 60 wt%; more preferably, 45 to 55 wt%; most preferably, 48 to 54 wt%) , based on dry weight of the gradient polymer, of structural monomer units of C_1-8 alkyl (meth) acrylate monomer; (c) ＞ 10 to 30 wt% (preferably, 12 to 30 wt%; more preferably, 15 to 25 wt%; most preferably, 16 to 20 wt%) , based on dry weight of the gradient polymer, of structural monomer units of a specialized associative monomer having structure I; wherein the specialized associative monomer having structure I is a blend of a first specialized associative monomer having structure Ia (preferably, 51 to 99 wt%; more preferably, 75 to 97 wt%; most preferably, 85 to 95 wt%) , based on weight of the specialized associative monomer having structure I, of the first specialized associative monomer having structure Ia)
wherein each R^1a is independently selected from a linear saturated C_12-19 alkyl group (preferably, a linear saturated C_12-18 alkyl group; more preferably, a linear saturated C_14-18 alkyl group; most preferably, a linear saturated C_16-18 alkyl group) ; wherein each R^2a is independently selected from a hydrogen and a methyl group (preferably, wherein R² is a methyl group) and wherein na is 10 to 30 (preferably, 12 to 30; more preferably, 15 to 28; most preferably, 18 to 26) ; and a second specialized associative monomer having structure Ib (preferably, 1 to 49 wt%; more preferably, 3 to 25 wt%; most preferably, 6 to 15 wt%) , based on weight of the specialized associative monomer having structure I, of the first specialized associative monomer having structure Ib)
wherein each R^1b is independently selected from a linear saturated C_20-26 alkyl group (preferably, a linear saturated C_20-24 alkyl group; more preferably, a linear saturated C_21-23 alkyl group; most preferably, a linear saturated C₂₂ alkyl group) ; wherein each R^2b is independently selected from a linear saturated hydrogen and a methyl group (preferably, a methyl group) and wherein nb is 10 to 30 (preferably, 15 to 30; more preferably, 18 to 28; most preferably, 20 to 28) ; and (d) 0.01 to 2 wt% (preferably, 0.05 to 1 wt%; more preferably, 0.08 to 0.5 wt%; most preferably, 0.1 to 0.2 wt%) , based on dry weight of the gradient polymer, of structural monomer units of multiethylenically unsaturated monomer; wherein the gradient polymer comprises ＜ 0.05 wt% (preferably, ＜ 0.01 wt%; more preferably, ＜ 0.001 wt%; still more preferably, ＜ 0.0001 wt%; most preferably, less than detectable limit) , based on dry weight of the gradient polymer, of structural monomer units of sulfonated monomer (e.g., AMPS) ; wherein the gradient polymer comprises ＜ 0.02 wt%, based on dry weight of the gradient polymer, (preferably, ＜ 0.01 wt%; more preferagbly, ＜ 0.001 wt%; still more preferably, ＜ 0.0001 wt%; most preferably, less than detectable limit) of structural monomer units of monomer having structure II, wherein each R³ is independently selected from -H and -CH₃; wherein each R⁴ is independently selected from -H and a -C_1-4 alkyl group; wherein each R⁵ is independently selected from a -C_1-4 alkyl group; wherein a is 0 to 50; wherein b is 0 to 20; wherein c is 0 to 50; wherein a + c is 1 to 100 and wherein d is 1 to 4; and wherein the gradient polymer has a gradient polymeric morphology.
Preferably, the gradient polymer of the present invention comprises 90 to 100 wt% (preferably, 95 to 100 wt%; more preferably, 98 to 100 wt%; still more preferably, 99 to 100 wt%; yet more preferably, 99.9 to 100 wt%; most preferably, 100 wt%) of the structural monomer units present in the gradient polymer are structural monomer units of (a) - (d) . The structural monomer units of the gradient polymer do not include end groups on the gradient polymer derived from chain transfer agent or initiator (e.g., residues of chain transfer agent) .
Preferably, the gradient polymer of the present invention comprises 5 to 35 wt% (preferably, 10 to 35 wt%; more preferably, 20 to 34 wt%; most preferably, 26 to 32 wt%) , based on dry weight of the gradient polymer, of structural monomer units of (meth) acrylic acid monomer; wherein the (meth) acrylic acid monomer is selected from the group consisting of methacrylic acid, acrylic acid and mixtures thereof. More preferably, the gradient polymer of the present invention comprises 5 to 35 wt% (preferably, 10 to 35 wt%; more preferably, 20 to 34 wt%; most preferably, 26 to 32 wt%) , based on dry weight of the gradient polymer, of structural monomer units of (meth) acrylic acid monomer; wherein the (meth) acrylic acid monomer is a mixture of methacrylic acid and acrylic acid. Most preferably, the gradient polymer of the present invention comprises 5 to 35 wt% (preferably, 10 to 35 wt%; more preferably, 20 to 34 wt%; most preferably, 26 to 32 wt%) , based on dry weight of the gradient polymer, of structural monomer units of (meth) acrylic acid monomer; wherein the (meth) acrylic acid monomer is a mixture of 30 to 60 wt% (preferably, 32 to 58 wt%; more preferably, 33 to 55 wt%) , based on weight of the mixture, of methacrylic acid and 40 to 70 wt%(preferably, 32 to 58 wt%; more preferably, 33 to 55 wt%) , based on weight of the mixture, of acrylic acid.
Preferably, the gradient polymer of the present invention comprises 35 to 65 wt% (preferably, 40 to 60 wt%; more preferably, 45 to 55 wt%; most preferably, 48 to 54 wt%) , based on dry weight of the gradient polymer, of structual units of C_1-8 alkyl (meth) acrylate monomer (preferably, C_1-6 alkyl (meth) acrylate monomer; more preferably, C_2-3 alkyl (meth) acrylate monomer; most preferably, C₂ alkyl acrylate monomer) . More preferably, the gradient polymer of the present invention comprises 35 to 65 wt% (preferably, 40 to 60 wt%; more preferably, 45 to 55 wt%; most preferably, 48 to 54 wt%) , based on dry weight of the gradient polymer, of structual units of C_1-8 alkyl (meth) acrylate monomer; wherein the C_1-8 alkyl (meth) acrylate monomer is selected from the group consisting of ethyl (meth) acrylate, propyl (meth) acrylate and mixtures thereof (preferably, ethyl acrylate, propyl acrylate and mixtures thereof) . Most preferably, the gradient polymer of the present invention comprises 35 to 65 wt% (preferably, 40 to 60 wt%; more preferably, 45 to 55 wt%; most preferably, 48 to 54 wt%) , based on dry weight of the gradient polymer, of structual units of C_1-8 alkyl (meth) acrylate monomer; wherein the C_1-8 alkyl (meth) acrylate monomer is ethyl acrylate.
Preferably, the gradient polymer of the present invention comprises ＞ 10 to 30 wt% (preferably, 12 to 30 wt%; more preferably, 15 to 25 wt%; most preferably, 16 to 20 wt%) , based on dry weight of the gradient polymer, of structural monomer units of a specialized associative monomer having structure I
wherein each R¹ is independently selected from a linear saturated C_12-26 alkyl group (preferably, C_12-24 alkyl group; more preferably, C_14-24 alkyl group; most preferably, C_16-22 alkyl group) ; wherein each R² is independently selected from a hydrogen and a methyl group (preferably, wherein R² is a methyl group) and wherein n is 10 to 30 (preferably, 12 to 30; more preferably, 15 to 28; most preferably, 18 to 26) . More preferably, the gradient polymer of the present invention comprises ＞ 10 to 30 wt% (preferably, 12 to 30 wt%; more preferably, 15 to 25 wt%; most preferably, 16 to 20 wt%) , based on dry weight of the gradient polymer, of structural monomer units of a specialized associative monomer having structure I; wherein the specialized associative monomer having structure I is a blend of a first specialized associative monomer having structure Ia (preferably, 51 to 99 wt%; more preferably, 75 to 97 wt%; most preferably, 85 to 95 wt%) , based on weight of the specialized associative monomer having structure I, of the first specialized associative monomer having structure Ia)
wherein each R^1a is independently selected from a linear saturated C_12-19 alkyl group (preferably, a linear saturated C_12-18 alkyl group; more preferably, a linear saturated C_14-18 alkyl group; most preferably, a linear saturated C_16-18 alkyl group) ; wherein each R^2a is independently selected from a hydrogen and a methyl group (preferably, wherein R² is a methyl group) and wherein na is 10 to 30 (preferably, 12 to 30; more preferably, 15 to 28; most preferably, 18 to 26) ; and a second specialized associative monomer having structure Ib (preferably, 1 to 49 wt%; more preferably, 3 to 25 wt%; most preferably, 6 to 15 wt%) , based on weight of the specialized associative monomer having structure I, of the first specialized associative monomer having structure Ib)
wherein each R^1b is independently selected from a linear saturated C_20-26 alkyl group (preferably, a linear saturated C_20-24 alkyl group; more preferably, a linear saturated C_21-23 alkyl group; most preferably, a linear saturated C₂₂ alkyl group) ; wherein each R^2b is independently selected from a linear saturated hydrogen and a methyl group (preferably, a methyl group) ; and wherein nb is 10 to 30 (preferably, 15 to 30; more preferably, 18 to 28; most preferably, 20 to 28) (preferably, wherein R^1a and R^1b differ by less than 8 carbon atoms (more preferably, by less than 7 carbon atoms) ) .
Preferably, the gradient polymer of the present invention comprises 0.01 to 2 wt% (preferably, 0.05 to 1 wt%; more preferably, 0.08 to 0.5 wt%; most preferably, 0.1 to 0.2 wt%) , based on dry weight of the gradient polymer, of structural monomer units of multiethylenically unsaturated monomer. More preferably, the gradient polymer of the present invention comprises 0.01 to 2 wt% (preferably, 0.05 to 1 wt%; more preferably, 0.08 to 0.5 wt%; most preferably, 0.1 to 0.2 wt%) , based on dry weight of the gradient polymer, of structural monomer units of multiethylenically unsaturated monomer; wherein the multiethylenically unsaturated monomer is selected from the group consisting of polyunsaturated aromatic monomers (e.g., divinyl benzene, divinyl naphthalene, trivinyl benzene) ; polyunsaturated alicyclic monomers (e.g., 1, 2, 4-trivinylcyclohexane) ; difunctional esters of phthalic acid (e.g., diallyl phthalate) ; polyunsaturated aliphatic monomers (e.g., isoprene, butadiene, 1, 5-hexadiene, 1, 5, 9-decatriene, 1, 9-decadiene, 1, 5-heptadiene) ; polyalkenyl ethers (e.g., trially pentaerythritol, diallyl pentaerythritol, diallyl sucrose, octaally sucrose, trimethylolpropane dially ether) ; polyunsaturated esters of polyalcohols or polyacids (e.g., 1, 6-hexanediol di (meth) acrylate, tetramethylene tri (meth) acrylate, allyl acrylate, diallyl itaconate, diallyl fumarate, diallyl maleat, trimethylolpropane tri (meth) acrylate, trimethylolpropane di (meth) acrylate, polyethylene glycol di (meth) acrylate) ; alkylene bisacrylamides (e.g., methylene bisacrylamide, propylene bisacrylamide) ; hydroxy and carboxy derivatives of methylene bis-acrylamide (e.g., N, N′-bismethylol methylene bisacrylamide) ; polyethyleneglycol di (meth) acrylates (e.g., ethyleneglycol di (meth) acrylate, diethyleneglycol di (meth) acrylate, triethyleneglycol di (meth) acrylate) ; polyunsaturated silanes (e.g., dimethyldivinylsilane, methyltrivinylsilane, allyldimethylvinylsilane, diallydimethylsilane, tetravinylsilane) ; polyunsaturated stannanes (e.g., tetraallyl tin, diallyldimethyl tin) and mixtures thereof. Still more preferably, the gradient polymer of the present invention comprises 0.01 to 2 wt% (preferably, 0.05 to 1 wt%; more preferably, 0.08 to 0.5 wt%; most preferably, 0.1 to 0.2 wt%) , based on dry weight of the gradient polymer, of structural monomer units of multiethylenically unsaturated monomer; wherein the multiethylenically unsaturated monomer is a polyalkenyl ether. Most preferably, the gradient polymer of the present invention comprises 0.01 to 2 wt% (preferably, 0.05 to 1 wt%; more preferably, 0.08 to 0.5 wt%; most preferably, 0.1 to 0.2 wt%) , based on dry weight of the gradient polymer, of structural monomer units of multiethylenically unsaturated monomer; wherein the multiethylenically unsaturated monomer is trimethylolpropane diallyl ether.
Preferably, the gradient polymer of the present invention further comprises 0.01 to 2 wt% (preferably, 0.02 to 1 wt%; more preferably, 0.04 to 0.5 wt%; most preferably, 0.06 to 0.1 wt%) , based on dry weight of the gradient polymer, of residues of chain transfer agent. More preferably, the gradient polymer of the present invention further comprises 0.01 to 2 wt%(preferably, 0.02 to 1 wt%; more preferably, 0.04 to 0.5 wt%; most preferably, 0.06 to 0.1 wt%) , based on dry weight of the gradient polymer, of residues of chain transfer agent; wherein the chain transfer agent is selected from the group consisting of thio and disulfide containing compounds (e.g., C_1-18 alkyl mercaptans, mercaptocarboxylic acids, mercaptocarboxylic esters, thioesters, C_1-18 alkyl disulfides, aryldisulfides, polyfunctional thiols) ; phosphites and hypophosphites; haloalkyl compounds (e.g., carbon tetrachloride, bromotrichloromethane) ; unsaturated chain transfer agents (e.g., alpha-methylstyrene) and mixtures thereof. Still more preferably, the gradient polymer of the present invention further comprises 0.01 to 2 wt% (preferably, 0.02 to 1 wt%; more preferably, 0.04 to 0.5 wt%; most preferably, 0.06 to 0.1 wt%) , based on dry weight of the gradient polymer, of residues of chain transfer agent; wherein the chain transfer agent is a C_1-18 alkyl mercaptan. Most preferably, the gradient polymer of the present invention further comprises 0.01 to 2 wt% (preferably, 0.02 to 1 wt%; more preferably, 0.04 to 0.5 wt%; most preferably, 0.06 to 0.1 wt%) , based on dry weight of the gradient polymer, of residues of chain transfer agent; wherein the chain transfer agent is n-dodecyl mercaptan.
Preferably, the gradient polymer of the present invention comprises ＜ 0.05 wt% (preferably, ＜ 0.01 wt%; more preferably, ＜ 0.001 wt%; still more preferably, ＜ 0.0001 wt%; most preferably, less than detectable limit) , based on dry weight of the gradient polymer, of structural monomer units of sulfonated monomer; wherein the sulfonated monomer is selected from the group consisting of 2-acrylamido-2-methylpropane sulfonic acid (AMPS) , 2-methacrylamido-2-methylpropane sulfonic acid, 4-styrenesulfonic acid, vinyl sulfonic acid, 3-allyloxy sulfonic acid, 2-hydroxy-1-propane sulfonic acid (HAPS) , 2-sulfoethyl (meth) acrylic acid, 2-sulfopropyl (meth) acrylic acid, 3-sulfopropyl (meth) acrylic acid, 4-sulfobutyl (meth) acrylic acid, salts thereof and mixtures thereof.
Preferably, the gradient polymer of the present invention comprises ＜ 0.02 wt%, based on dry weight of the gradient polymer, (preferably, ＜ 0.01 wt%; more preferably, ＜ 0.001 wt%; still more preferably, ＜ 0.0001 wt%; most preferably, less than detectable limit) of structural monomer units of monomer having structure II
wherein each R³ is independently selected from -H and -CH₃; wherein each R⁴ is independently selected from -H and a -C_1-4 alkyl group; wherein each R⁵ is independently selected from a -C_1-4 alkyl group; wherein a is 0 to 50; wherein b is 0 to 20; wherein c is 0 to 50;wherein a + c is 1 to 100 and wherein d is 1 to 4.
Preferably, the gradient polymer of the present invention comprises ＜ 0.01 wt% (preferably, ＜ 0.005 wt%; more preferably, ＜ 0.001 wt%; still more preferably, ＜ 0.0001 wt%; most preferably, less than detectable limit) , based on dry weight of the gradient polymer, of structural monomer units of monomer selected from the group consisting of styrene, butyl acrylate, ethylhexyl acrylate, lauryl acrylate, stearyl acrylate, methyl methacrylate and mixtures thereof.
Preferably, the gradient polymer of the present invention comprises ＜ 2 wt% (preferably, ＜ 1 wt%; more preferably, ＜ 0.5 wt%; still more preferably, ＜ 0.1 wt%; yet more preferably, ＜ 0.01 wt%; still yet more preferably, ＜ 0.001 wt%; most preferably, less than detectable limit) , based on dry weight of the gradient polymer, of structural monomer units of monomer selected from the group consisting of C_6-18 alkyl (meth) acrylate, vinyl alkanoate having 6 to 18 carbon atoms, N-vinyl alkylamide having 6 to 18 carbon atoms, N-alkyl (meth) acrylamide having 6 to 18 carbon atoms and mixtures thereof.
Preferably, the gradient polymer of the present invention comprises: (a) 5 to 35 wt% (preferably, 10 to 35 wt%; more preferably, 20 to 34 wt%; most preferably, 26 to 32 wt%) , based on dry weight of the gradient polymer, of structural monomer units of (meth) acrylic acid monomer; (b) 35 to 65 wt% (preferably, 40 to 60 wt%; more preferably, 45 to 55 wt%; most preferably, 48 to 54 wt%) , based on dry weight of the gradient polymer, of structural monomer units of C_1-8 alkyl (meth) acrylate monomer; (c) ＞ 10 to 30 wt% (preferably, 12 to 30 wt%; more preferably, 15 to 25 wt%; most preferably, 16 to 20 wt%) , based on dry weight of the gradient polymer, of structural monomer units of a specialized associative monomer having structure I; wherein the specialized associative monomer having structure I is a blend of a first specialized associative monomer having structure Ia (preferably, 51 to 99 wt%; more preferably, 75 to 97 wt%; most preferably, 85 to 95 wt%) , based on weight of the specialized associative monomer having structure I, of the first specialized associative monomer having structure Ia) , wherein each R^1a is independently selected from a linear saturated C_12-19 alkyl group (preferably, a linear saturated C_12-18 alkyl group; more preferably, a linear saturated C_14-18 alkyl group; most preferably, a linear saturated C_16-18 alkyl group) ; wherein each R^2a is independently selected from a hydrogen and a methyl group (preferably, wherein R² is a methyl group) and wherein na is 10 to 30 (preferably, 12 to 30; more preferably, 15 to 28; most preferably, 18 to 26) ; and a second specialized associative monomer having structure Ib (preferably, 1 to 49 wt%; more preferably, 3 to 25 wt%; most preferably, 6 to 15 wt%) , based on weight of the specialized associative monomer having structure I, of the first specialized associative monomer having structure Ib) , wherein each R^1b is independently selected from a linear saturated C_20-26 alkyl group (preferably, a linear saturated C_20-24 alkyl group; more preferably, a linear saturated C_21-23 alkyl group; most preferably, a linear saturated C₂₂ alkyl group) ; wherein each R^2b is independently selected from a linear saturated hydrogen and a methyl group (preferably, a methyl group) and wherein nb is 10 to 30 (preferably, 15 to 30; more preferably, 18 to 28; most preferably, 20 to 28) ; and (d) 0.01 to 2 wt% (preferably, 0.05 to 1 wt%; more preferably, 0.08 to 0.5 wt%; most preferably, 0.1 to 0.2 wt%) , based on dry weight of the gradient polymer, of structural monomer units of multiethylenically unsaturated monomer; wherein the gradient polymer comprises ＜ 0.05 wt% (preferably, ＜ 0.01 wt%; more preferably, ＜ 0.001 wt%; still more preferably, ＜ 0.0001 wt%; most preferably, less than detectable limit) , based on dry weight of the gradient polymer, of structural monomer units of sulfonated monomer (e.g., AMPS) ; wherein the gradient polymer comprises ＜ 0.02 wt%, based on dry weight of the gradient polymer, (preferably, ＜ 0.01 wt%; more preferably, ＜ 0.001 wt%; still more preferably, ＜ 0.0001 wt%; most preferably, less than detectable limit) of structural monomer units of monomer having structure II, wherein each R³ is independently selected from -H and -CH₃; wherein each R⁴ is independently selected from -H and a -C_1-4 alkyl group; wherein each R⁵ is independently selected from a -C_1-4 alkyl group; wherein a is 0 to 50; wherein b is 0 to 20; wherein c is 0 to 50; wherein a + c is 1 to 100 and wherein d is 1 to 4; wherein the gradient polymer has a gradient polymeric morphology; and with any one or more of the following provisos (i) - (v) : (i) wherein R^1a and R^1b differ by less than 8 carbon atoms (preferably, ＜ 7 carbon atoms) ; (ii) wherein the structural monomer units of (meth) acrylic acid monomer include structural monomer units of both methacrylic acid and acrylic acid; (iii) wherein the gradient polymer comprises ＜ 0.01 wt% (preferably, ＜ 0.005 wt%; more preferably, ＜ 0.001 wt%; still more preferably, ＜ 0.0001 wt%; most preferably, less than detectable limit) , based on dry weight of the gradient polymer, of structural monomer units of monomer selected from the group consisting of styrene, butyl acrylate, ethylhexyl acrylate, lauryl acrylate, stearyl acrylate, methyl methacrylate, butyl acrylate and mixtures thereof; (iv) wherein the gradient polymer comprises ＜ 2 wt% (preferably, ＜ 1 wt%; more preferably, ＜ 0.5 wt%; still more preferably, ＜ 0.1 wt%; yet more preferably, ＜ 0.01 wt%; still yet more preferably, ＜ 0.001 wt%; most preferably, less than detectable limit) , based on dry weight of the gradient polymer, of structural monomer units of monomer selected from the group consisting of alkyl (meth) acrylate having 6 to 18 carbon, vinyl alkanoate having 6 to 18 carbon atoms, N-vinyl alkylamide having 6 to 18 carbon atoms, N-alkyl (meth) acrylamide having 6 to 18 carbon atoms and mixtures thereof; and/or (v) wherein the gradient polymer comprises 90 to 100 wt% (preferably, 95 to 100 wt%; more preferably, 98 to 100 wt%; still more preferably, 99 to 100 wt%; yet more preferably, 99.9 to 100 wt%; most preferably, 100 wt%) of the structural monomer units present in the gradient polymer are structural monomers units of (a) - (d) .
Some embodiments of the present invention will now be described in detail in the following Examples.
Synthesis S1: Gradient polymer
To a 3 L, 4 necked round bottom reactor equipped with a mechanical stirrer, thermocouple, condenser, and nitrogen sparge was added deionized water (350 g) and sodium lauryl sulfate (9.1 g) . The reactor was purged with nitrogen and warmed to 85℃. Separately the following were prepared, namely: (1) a monomer emulsion A was prepared from deionized water (450 g) ; sodium lauryl sulfate (16.4 g) ; ethyl acrylate (EA) (262 g) ; a lipophilically modified monomer (Lipo 1) (82.1 g) having the following structure
wherein R¹ was a linear saturated C_16-18 alkyl group and n was an average of 18 to 26; a lipophilically modified monomer (Lipo 2) (9.6 g) having the following structure
wherein R¹ was a linear saturated C₂₂ alkyl group and n was an average of 20 to 28; methacrylic acid (MAA_A) (45.68 g) ; acrylic acid (AA) (101.1 g) and n-dodecyl mercaptan (n-DDM) (0.4 g) ; (2) a monomer emulsion additive B was prepared by mixing deionized water (70 g) ; sodium lauryl sulfate (9.1 g) ; trimethylolpropane dially ether (x-link) (0.81 g) and methacrylic acid (MAA_B) (4.82 g) ; (3) an initiator solution (C1) was prepared by dissolving ammonium persulfate (0.35 g) in deionized water (15 g) and (4) an initiator solution (C2) was prepared by dissolving ammonium persulfate (0.55 g) in deionized water (84 g) . At ～85 ℃ reactor temperature, the reactor was charged with initiator solution (C1) . Then monomer emulsion (A) was charged into the reactor while monomer emulsion additive (B) was charged simultaneously into monomer emulsion (A) . The rate was controlled so that the feed of monomer emulsion (A) started at 1/2 x speed during the first 10 minutes and at 1x speed until finished at 120 min. and where feed of monomer emulsion additive (B) finished in 100 min. Simultaneously, initiator solution (C2) was feed into the reactor over 125 min. After these additions were completed, the monomer emulsion and initiator feed lines were rinsed with deionized water followed with monomer chasing with free radical catalyst and activator.
Syntheses S2-S4: Gradient polymer
The gradient polymers in Syntheses S2-S4 were prepared according to the procedure descrived in Synthesis S1 except with the composition changes as described in TABLE 1.
Synthesis S5: Non-gradient polymer
To a 3 L, 4 necked round bottom reactor equipped with a mechanical stirrer, thermocouple, condenser, and nitrogen sparge was added deionized water (275 g) and sodium lauryl sulfate (9.1 g) . The reactor was purged with nitrogen and warmed to 85℃. Separately the following were prepared, namely: (1) a monomer emulsion A was prepared from deionized water (570 g) ; sodium lauryl sulfate (25.5 g) ; ethyl acrylate (EA) (262 g) ; a lipophilically modified monomer (Lipo 1) (82.1 g) having the following structure
wherein R¹ was a linear saturated C_16-18 alkyl group and n was an average of 18 to 26; a lipophilically modified monomer (Lipo 2) (9.6 g) having the following structure
wherein R¹ was a linear saturated C₂₂ alkyl group and n was an average of 20 to 28; methacrylic acid (MAA) (50.5 g) ; acrylic acid (AA) (101.1 g) ; n-dodecyl mercaptan (n-DDM) (0.4 g) and trimethylolpropane dially ether (x-link) (0.81 g) ; (2) an initiator solution (C1) was prepared by dissolving ammonium persulfate (0.35 g) in deionized water (15 g) and (3) an initiator solution (C2) was prepared by dissolving ammonium persulfate (0.55 g) in deionized water (84 g) . At ～85 ℃ reactor temperature, the reactor was charged with initiator solution (C1) . Then monomer emulsion (A) was charged into the reactor. The rate was controlled so that the feed of monomer emulsion (A) started at 1/2 x speed during the first 10 minutes and at 1x speed until finished at 120 min. Separately, initiator solution (C1) was started simultaneously with the feed of monomer emulsion (A) and was fed into the reactor over 125 min. After these additions were completed, the monomer and initiator feed lines were rinsed with deionized water followed with monomer chasing with free radical catalyst and activator.
Syntheses S6-S8: Non-gradient polymer
The non-gradient polymers in Syntheses S6-S8 were prepared according to the procedure descrived in Synthesis S5 except with the composition changes as described in TABLE 2.
Viscosity and Turbidity Measurements
Solubilized viscosity and turbidity of solution containing 0.75%polymer active was determined for each of the polymers prepared according to Syntheses S1-S8 as reported in TABLE 3 using the following procedure:
1. Weighed out sufficient polymer to provide 0.75%polymer in final formulation.
2. Prediluted with deionized water to make 169 g solution.
3. Added 11.0 g of 20%w/w sodium hydroxide solution in water and stirred efficiently with overhead stirrer until homogenous.
4. Equilibrated in a war water bath for 10-15 min. so the internal temperature of the solution was 20 ℃.
5. Measured pH between 7.8 to 10. Adjusted with 20%sodium hydroxide as necessary.
6. Measured viscosity at 20 ℃ and 0.3, 3, 6, 12, 20, 30 and 60 rpm using Brookfield viscometer with corresponding spindles to obtain measurements with at least 10%of scale.
7. Transferred sample into 1 oz vial for turbidity measurement.
8. Spun 1 oz vials on centrifuge at 3, 500 rpm for 20 min.
9. Measured turbidity in Nephelometric Turbidity Units (NTU) on turbidity meter at 20 ℃.
Results of viscosity and turbidity measurements are reported in TABLE 3.
Comparative Examples CF1-CF6 and Examples F1-F6: Cleansing Formulations
Aqueous personal care cleansing formulations were prepared in each of Comparative Examples CF1-CF6 and Examples F1-F6 having the formulations noted in TABLE 4.
The Phase A components, if any, for each of Comparative Examples CF1-CF6 and Examples F1-F6 were mixed with mild agitation until dissolved. The Phase B components were mixed together in a separate container. The mixed Phase B components were then slowly added into the mixed Phase A components, if any. The Phase C components were then added into the mixed Phase A, if any, and Phase B components. The appropriate Phase D component was then mixed in as need to adjust to the pH noted in TABLE 4. The viscosity of the resulting aqueous personal care cleaning formulation was then measured at 20 ℃ using Brookfield viscometer with correspondent spindles as listed in TABLE 5.
Comparative Examples CF7-CF10 and Examples F7-F10: Cleansing Formulations
Aqueous personal care cleansing formulations were prepared in each of Comparative Examples CF7-CF10 and Examples F7-F10 having the formulations noted in TABLE 6. The Phase A components were mixed together. The mixed Phase B components were then slowly added into the mixed Phase A components. The appropriate Phase C component was mixed into the mixed Phase A and Phase B components as needed to adjust the pH. The viscosity of the resulting aqueous personal care cleaning formulation was then measured at 20 ℃ using Brookfield viscometer with correspondent spindles at 20 rpm as listed in TABLE 7. The turbidity of each formulation was measured using a Micro 100 Turbidimeter (HF Scientific, Inc. ) as listed in TABLE 7.
Rheological Data
The rheology of the aqueous personal care cleansing formulations prepared according to Comparative Examples CF7-CF10 and Examples F7-F10 were characterized using a Discovery HR-3 Hybrid Rheometer (TA Instruments) with 40 mm parallel plate geometry. All testing was done at 25 ℃. The tests included amplitude sweep with oscillation displacement from 0.0002 to 0.15 rad at 1 rad/s, and a flow sweep at shear rate of 0.01 to 500 s^-1. The G’ , G” and tan δ values were obtained from the amplitude in the linear viscoelastic region, and the viscosity values were obtained from the shear rate sweep as listed in TABLE 8.

Claims

A gradient polymer comprising:

(a) 5 to 35 wt%, based on dry weight of the gradient polymer, of structural monomer units of (meth) acrylic acid monomer;

(b) 35 to 65 wt%, based on dry weight of the gradient polymer, of structural monomer units of C_1-8 alkyl (meth) acrylate monomer;

(c) > 10 to 30 wt%, based on dry weight of the gradient polymer, of structural monomer units of a specialized associative monomer having structure I

wherein each R¹ is independently selected from a linear saturated C_12-26 alkyl group; wherein each R² is independently selected from a hydrogen and a methyl group and wherein n is 10 to 30;

(d) 0.01 to 2 wt%%, based on dry weight of the gradient polymer, of structural monomer units of multiethylenically unsaturated monomer;

wherein the gradient polymer comprises ＜ 0.05 wt%, based on dry weight of the gradient polymer, of structural monomer units of sulfonated monomer;

wherein the gradient polymer comprises ＜ 0.02 wt%, based on dry weight of the gradient polymer, of structural monomer units of monomer having structure II

wherein each R³ is independently selected from -H and -CH₃; wherein each R⁴ is independently selected from -H and a -C_1-4 alkyl group; wherein each R⁵ is independently selected from a -C_1-4 alkyl group; wherein a is 0 to 50; wherein b is 0 to 20; wherein c is 0 to 50;wherein a + c is 1 to 100; and wherein d is 1 to 4; and

wherein the gradient polymer has a gradient polymeric morphology.
The gradient polymer of claim 1, wherein the structural monomer units of specialized associative monomer having structure I is a blend of

a first specialized associative monomer having structure Ia

wherein each R^1a is independently selected from a linear saturated C_12-19 alkyl group; wherein each R^2a is independently selected from a hydrogen and a methyl group and wherein na is 10 to 30; and

a second specialized associative monomer having structure Ib

wherein each R^1b is independently selected from a linear saturated C_20-26 alkyl group; wherein each R^2b is independently selected from a linear saturated hydrogen and a methyl group; and wherein nb is 10 to 30.
The gradient polymer of claim 1, wherein the structural monomer units of (meth) acrylic acid monomer include structural monomer units of both methacrylic acid and acrylic acid.
The gradient polymer of claim 1, wherein the gradient polymer comprises ＜ 0.01 wt%, based on dry weight of the gradient polymer, of structural monomer units of monomer selected from the group consisting of styrene, butyl acrylate, ethylhexyl acrylate, lauryl acrylate, stearyl acrylate, methyl methacrylate, butyl acrylate and mixtures thereof.
The gradient polymer of claim 1, wherein the gradient polymer comprises ＜ 2 wt%, based on dry weight of the gradient polymer, of monomer selected from the group consisting of alkyl (meth) acrylate having 6 to 18 carbon, vinyl alkanoate having 6 to 18 carbon atoms, N-vinyl alkylamide having 6 to 18 carbon atoms, N-alkyl (meth) acrylamide having 6 to 18 carbon atoms and mixtures thereof.
The gradient polymer of claim 1, wherein the gradient polymer comprises 90 to 100 wt%of the structural monomer units present in the gradient polymer are structural monomers units of (a) - (d) .
The gradient polymer of claim 2, wherein the gradient polymer comprises ＜ 0.01 wt%, based on dry weight of the gradient polymer, of structural monomer units of monomer selected from the group consisting of styrene, butyl acrylate, ethylhexyl acrylate, lauryl acrylate, stearyl acrylate, methyl methacrylate, butyl acrylate and mixtures thereof.
The gradient polymer of claim 2, wherein R^1a and R^1b differ by less than 8 carbon atoms.
The gradient polymer of claim 2, wherein the gradient polymer comprises ＜ 2 wt%, based on dry weight of the gradient polymer, of structural monomer units of monomer selected from the group consisting of alkyl (meth) acrylate having 6 to 18 carbon, vinyl alkanoate having 6 to 18 carbon atoms, N-vinyl alkylamide having 6 to 18 carbon atoms, N-alkyl (meth) acrylamide having 6 to 18 carbon atoms and mixtures thereof.
The gradient polymer of claim 2, with any one or more of the following provisos (i) - (v) :

(i) wherein R^1a and R^1b differ by less than 8 carbon atoms;

(ii) wherein the structural monomer units of (meth) acrylic acid monomer include structural monomer units of both methacrylic acid and acrylic acid;

(iii) wherein the gradient polymer comprises ＜ 0.01 wt%, based on dry weight of the gradient polymer, of structural monomer units of monomer selected from the group consisting of styrene, butyl acrylate, ethylhexyl acrylate, lauryl acrylate, stearyl acrylate, methyl methacrylate, butyl acrylate and mixtures thereof;

(iv) wherein the gradient polymer comprises ＜ 2 wt%, based on dry weight of the gradient polymer, of structural monomer units of monomer selected from the group consisting of alkyl (meth) acrylate having 6 to 18 carbon, vinyl alkanoate having 6 to 18 carbon atoms, N-vinyl alkylamide having 6 to 18 carbon atoms, N-alkyl (meth) acrylamide having 6 to 18 carbon atoms and mixtures thereof; and/or

(v) wherein the gradient polymer comprises 90 to 100 wt%of the structural monomer units present in the gradient polymer are structural monomers units of (a) - (d) .